It is intended to investigate experimentally (in rhesus monkeys) and pathologically retinal and uveal vascular disorders. The uveal circulation in health and disease will be investigated systematically to determine (a) its anatomy, (b) its dynamics in health and in various occlusive disorders, (c) the ocular lesions produced by occlusion of various ciliary vessels, and (d) the role of posterior ciliary ischemia in glaucoma, low-tension glaucoma and ischemic optic neuropathy. In (a) ischemic, (b) hemorrhagic, and (c) venous stasis retinopathy, it is our intention to study (1) the time required for the retinal ischemia to produce functional and anatomical deaths in the retina and its various components, and various factors influencing this, including the role of a wide variety of therapeutic regimens; (2) the natural history of retinal disease in a detailed prospective experimental study, and (3) the evolution of the retinal vascular dynamics. In all these studies, the assessments will be made (a) for the various ocular lesions, (b) for the circulatory dynamics by perfusion and fluorescein angiography, (c) for some of the retinal functions by electrophysiological testing, and (d) for pathological changes by histological and electron microscopical examination. BIBLIOGRAPHIC REFERENCES: Hayreh, S.S.: So-called "Central retinal vein occlusion" - I. Pathogenesis, Terminology and Clinical Features. Ophthalmologica (Basel) 172:1-13, 1976. Hayreh, S.S.: So-called "Central retinal vein occlusion" - II. Venous Stasis Retinopathy. Ophthalmologica (Basel) 172:14-37, 1976.